Lumenal proteins involved in respiratory electron transport in the cyanobacterium Synechocystis sp. PCC6803 |
| |
Authors: | Manna Pradip Vermaas Wim |
| |
Institution: | (1) Present address: Department of Biochemistry and Biophysics, Iowa State University, Ames, IA 50011, USA;(2) Molecular & Cellular Biology Program, Department of Botany and Center for the Study of Early Events in Photosynthesis, Arizona State University, Box 871601, Tempe, AZ 85287-1601, USA |
| |
Abstract: | Cyanobacterial thylakoids catalyze both photosynthetic and respiratory activities. In a photosystem I-less Synechocystis sp. PCC 6803 strain, electrons generated by photosystem II appear to be utilized by cytochrome oxidase. To identify the lumenal electron carriers (plastocyanin and/or cytochromes c
553, c
550, and possibly c
M) that are involved in transfer of photosystem II-generated electrons to the terminal oxidase, deletion constructs for genes coding for these components were introduced into a photosystem I-less Synechocystis sp. PCC 6803 strain, and electron flow out of photosystem II was monitored in resulting strains through chlorophyll fluorescence yields. Loss of cytochrome c
553 or plastocyanin, but not of cytochrome c
550, decreased the rate of electron flow out of photosystem II. Surprisingly, cytochrome c
M could not be deleted in a photosystem I-less background strain, and also a double-deletion mutant lacking both plastocyanin and cytochromec
553 could not be obtained. Cytochrome c
M has some homology with the cytochrome c-binding regions of the cytochromecaa3 -type cytochrome oxidase from Bacillus spp. and Thermus thermophilus. We suggest that cytochrome c
M is a component of cytochrome oxidase in cyanobacteria that serves as redox intermediate between soluble electron carriers and the cytochromeaa3 complex, and that either plastocyanin or cytochrome c
553 can shuttle electrons from the cytochrome b6f complex to cytochrome c
M. |
| |
Keywords: | cyanobacteria cytochrome oxidase electron transport photosynthesis respiration thylakoids |
本文献已被 SpringerLink 等数据库收录! |
|